Performance And Expansion Plans For The Double Displacement Process In The Hawkins Field Unit
- M.A. Langenberg (Exxon Company, U.S.A.) | D.M. Henry (Exxon Company, U.S.A.) | M.R. Chlebana (Exxon Company, U.S.A.)
- Document ID
- Society of Petroleum Engineers
- SPE Reservoir Engineering
- Publication Date
- November 1995
- Document Type
- Journal Paper
- 301 - 308
- 1995. Society of Petroleum Engineers
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- 787 since 2007
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This paper documents the initial Six years of the Double DisplacementProject in the East Fault Block of the Hawkins Field Unit, confirming theviability of the double displacement recovery mechanism. It describes how earlyproject performance indicated that oil gravity drainage was occurring slowerthan expected, the studies initiated to investigate the gravity drainage issue,and the successful outcome of those studies. Further, the paper describes howthe project has responded favorably to optimization efforts and how resultsfrom the East Fault Block have been applied to a proposed expansion to the WestFault Block.
The concept of Double Displacement as a recovery mechanism was introduced inSPE/DOE 17324, "Performance Of Hawkins Field Unit Under Gas Drive-PressureMaintenance Operations and Development of an Enhanced Oil RecoveryProject," by L.O. Carlson (1988). The Double Displacement Process (DDP)leads to increased recovery due to improved gravity drainage and sweepefficiency in the gas/oil system relative to the water/oil system atHawkins.
The Hawkins Field, discovered in 1940, is located in the southeast corner ofWood county, Texas, about 100 miles east of Dallas. The field is located in thecentral portion of the East Texas Woodbine Basin and shares a common aquiferwith East Texas, van, Neches, and other Woodbine Fields. The field was rapidlydeveloped to 20-acre spacing during the 1940s. The oil production rate peakedat 112,000 B0PD in 1975 and has since declined to a current rate of 12,000B0PD. Cumulative oil production is over 800 MMSTB.
Production is from the Woodbine formation of the Upper cretaceous age. TheWoodbine is divided into the upper Lewisville and the lower Dexter members(Figure 1). The Dexter sands were deposited by braided streams and tend to bethick, massive, and have good continuity throughout the reservoir. The Dextersands contained about 70 percent of the original oil in place. The Lewisvillesands, on the other hand, were deposited by meandering streams and tend to bemore lenticular and discontinuous in nature. Table I shows a comparison of theaverage rock properties for the two members as well as average properties forHawkins oil.
The Hawkins Field has about 1,200 feet of closure on the top of theWoodbine. The structure was generated by the upward thrust of a deep-seatedsalt dome which created extensive faulting in the Woodbine. Figure 2, astructure map on top of the Dexter sands, shows the fault patterns. Even withthis faulting there is good communication across most of the faults due tosand-to-sand juxtaposition, except for the large fault that runs from thenortheast to southwest on the eastern side of the field. This large faultseparates the field into two productive areas, the East Fault Block (EFB) andthe West Fault Block (WFB). The WFB contained approximately 80% of the originaloil in place. The field covers about 10,000 acres and had about 1,000 feet oftotal hydrocarbon column with an average formation dip of 60. The Woodbinereservoir originally contained over 1.3 billion barrels of oil and 430 Bscf ofgas cap gas.
Early in the development of the field it was realized that Hawkins containeda gravity-segregated oil column. In the WF8, the oil column degrades into a tarzone that is impermeable to oil and has a permeability to water of about 1 md.The asphalt approaches 100 foot thickness in the south and about 40-50 feet inthe north. In the EFB there is essentially no asphalt layer.
The presence or absence of this asphalt layer has played a major role in thedevelopment and performance of the field since its discovery. Production fromthe East Texas Field, which was discovered some 10 years prior to the Hawkinsdiscovery, had drawn down the aquifer pressure. The EFB, being open to theaquifer due to the absence of the asphalt layer, was discovered at a pressureof 1,716 psi, or the same as the aquifer pressure in that area. The EFBproduced under a strong water drive after it was placed on production. By 1974,cased-hole logging surveys indicated the oil column had invaded the Dexter gascap to the crest. Figure 3 is a graph of the production and injection historyfor the EFB.
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